The brass is safe to shoot as long as the outside neck diameter isn't so large that it would cause bullet impingement, which is a definite possibility when necking down. I would advise you not to shoot any of the Nosler until you figure this out.
+1
Just a possibility, but it warrants a check of neck thickness on a loaded round vs the chamber neck diameter on your gun. Perhaps the Nosler brass has thicker necks to begin with, and necking down always has the effect of making them even thicker.
Case necks being too long or too thick can both lead to dangerous chamber pressure issues.
If it's
only a slightly tight headspace issue, that's pretty safe and usually fixed with a FL die adjustment. FWIW, I've had factory ammo chamber a little tight in my 300 WSM. It didn't cause a problem as far as firing or pressure goes, but that gun does seem to have some accuracy issues.
Best of luck, but do check your chamber neck dimension vs the loaded round neck dimension. We need
at least .001" clearance to be safe, and that's pretty snug really. .002-.003 is mo better.
If for some reason you don't know the chamber neck diameter, a crude check is to see if your case will hold a bullet
without resizing it after it's been fired. Excess clearance will not hold a bullet generally, just right will hold a bullet but it can be moved in and out with your fingers, too tight is when it takes a seating die to even get a bullet in the case. These are crude generalizations, and vary with the softness of the brass and shape of bullet, but it's something to look at.
